The present invention relates to the field of optical communication and more particularly to a network-architecture for providing broadband communication between nodes.
Real-time computing applications make severe demands on both the computing and the communications infrastructure. Although the computing power offered by a single machine continues to increase, the complexity and scope for real-time applications has grown at a much faster rate. Most real-time applications such as RADAR processing, multimedia, medical imaging diagnostics, image processing, large database searching. tele-presence, and virtual reality require computing power beyond the capabilities of a single processing node.
In an effort to satisfy this demand a number of specialised parallel architectures have been built. However, most of these architectures were designed to have a fixed interconnection topology, often favorable to a particular type of application, with little flexibility for growth. As a result of this, recent approaches to interconnecting multiple independent processors are evolving away from a rigid parallel architecture towards a system area network. Interconnecting high performance computers in a system area network (SAN) has the potential to provide supercomputer performance to the desktop and access to new application areas which are beyond the computing power of an individual node. For example, tasks such as distributed database searching, multiple video streaming, and medical image searching-can be performed from any of a number of nodes taking advantage of computing resources throughout the network.
Latency is an important issue for interconnection in such an environment, particularly for applications where the expected communication between the nodes is high. Recent progress in optical broadband networking has shown a way to solve this problem and to assemble real-time computing power with low complexity and with high growth capability using a gigabit all-optical network. In particular, wavelength division multiplexing (WDM) has increased the useable bandwidth on a single fibre many times and is starting to influence the design of high performance networks.
In a common WDM star coupler based architecture, each node is provided with a single transmitter frequency and a plurality of receiver frequencies. The transmitter transmits at one fixed carrier frequency or wavelength channel. Hence, the maximum number of nodes remains related to the number of frequencies and the bandwidth to a node remains limited to the bandwidth of a frequency channel. Moreover, every node has a unique frequency assigned thereto. The number of nodes in the network is limited by the number of frequencies that are supported by the network. The resulting system becomes expensive, unscalable, and difficult to build for a large number of network nodes as is typically required.
In order to overcome these and other shortcomings of the prior art, it is an object of the invention to provide a star coupler based network architecture for high-bandwidth communication where a number of nodes in the network is not limited by a number of available frequency channels.
In accordance with the invention there is provided a communication node for use in a multi-wavelength optical communication network supporting communication at each of W wavelength wherein W greater than 2 comprising: an optical transmitter for transmitting data at each of a plurality of wavelengths the number of wavelengths less than the number W but greater than 1; an optical receiver for simultaneously receiving signals transmitted at each of the W wavelengths; and, control logic for dynamically allocating transmitter wavelength for use in providing a dedicated transmission channel from the node to another node within the optical communication network.
In accordance with another aspect of the invention there is provided a multi-wavelength optical communication network comprising: a WDM communication network supporting communication in W wavelength channels; N intercommunicating network nodes each including at least a transmitter for transmitting data via the WDM communication network at each of T wavelengths (0 less than 1xe2x89xa6W) and at least a receiver for receiving data transmitted via the WDM communication network on each of W wavelengths, some nodes having transmitters for transmitting at a same wavelength; and, a controller for dynamically allocating a transmit wavelength to a node within the N intercommunicating network nodes.
In accordance with another aspect of the invention there is provided a method of providing an optical communication network comprising the steps of: providing a WDM optical connection between each of a plurality of nodes; providing N intercommunicating network nodes each including a transmitter for transmitting data via the WDM communication network at each of T wavelengths (0 less than Txe2x89xa6W) and a receiver for receiving data transmitted via the WDM communication network on some of the W wavelengths. Preferably the receiver receives signals on all the W wavelengths simultaneously and individually. Some nodes have transmitters for transmitting at a same wavelength. The method also includes the steps of dynamically allocating a transmit wavelength to a first node within the N intercommunicating network nodes where the transmit wavelength allocation depends upon free wavelengths and transmit wavelengths supported by the transmitter of the first node; transmitting data from the first node to a second node at the allocated transmit wavelength; and, receiving data at the second node at each of the W wavelengths and extracting data directed to the second node.